The present invention relates to a cleaning apparatus and a cleaning method, by which objects to be processed, such as semiconductor wafers and glass substrates for a LCD (liquid crystal display) unit etc., are immersed and cleaned in chemical and subsequently dried.
For example, in a cleaning treatment of a manufacturing process for a semiconductor device, such as LSI etc., various cleaning apparatuses are employed for removing contaminants on the surfaces of the semiconductor wafers, such as particles, organic contaminants, metallic impurities and so on, and for etching the surface of the wafer. Note, in this specification, the semiconductor wafer(s) will be called the wafer(s) for short, hereinafter. Above all, a cleaning apparatus of xe2x80x9cwetxe2x80x9d type comes into wide use on the grounds that the above contaminants can be removed effectively, the etching can be done and a batch processing can be accomplished to enhance the throughput in the cleaning process.
In such a wet type of cleaning apparatus, the wafers to be cleaned are subjected to a chemical cleaning process (e.g. ammonia treatment, hydrogen fluoride treatment, sulfuric acid treatment etc.), a washing cleaning process using pure water etc., and a drying process using isopropyl alcohol [(CH3) 2CHOH] or the like. Note, the isopropyl alcohol will be referred the IPA, hereinafter. Further, the cleaning apparatus is so constructed to supply the chemicals, the pure water and the IPA to processing baths in processing order and a drying room, respectively. Thus, with the above arrangement, a batch processing method where the wafer in blocks of e.g. 50 sheets are successively immersed in the processing baths and dried in the drying room, comes into wide use.
However, the provision of the processing baths and the drying room for each process causes the apparatus to be large-sized undesirably. In addition, because of a lot of opportunities for transporting the wafers in the apparatus, in other words, being exposed to atmosphere, there is a great possibility of the particles"" sticking to the wafers.
Therefore, in e.g. Japanese Unexamined Patent Publication (kokai) No. 64-81230 and the same No. 6-326073 etc., there are proposed cleaning apparatuses in each of which the processing baths and the drying room are formed in one body, so that the above-mentioned chemical process and drying process are carried out in one chamber. FIG. 1 shows one example of the cleaning apparatuses in the publications, representatively.
The shown cleaning apparatus comprises a chamber 200 and chemical (liquid) 202 stored in a lower portion 201 of the chamber 200. In processing, a wafer W is firstly immersed in the chemical 202. Thereafter, the wafer W is pulled up from the chemical 202 and then subjected to the drying process using the IPA etc. at an upper portion 203 of the chamber 200.
In the above-mentioned drying process while heating, however, there is a possibility that chemical atmosphere remaining in an upper area of the chamber 200 exerts a bad influence on the wafer W during the drying process. Furthermore, since there is a need to meet respective requirements of the chemical and drying processes simultaneously, the degree of freedom is restricted in design of the cleaning apparatus. Therefore, it is difficult to adopt various ideas to realize a high-speed cleaning process, a miniaturization of the chamber and so on. Meanwhile, in the drying process using the above IPA etc., it is generally executed to decompress the chamber by using a vacuum pump or the like. However, since the chamber in the cleaning apparatus constructed above, in which the chemical treatment etc. and the sequent drying process are executed together, has to have a large capacity volume to a certain extent, there are problems to be solved that it is necessary to increase a wall thickness of the chamber in order to ensure the pressure tightness and a high power vacuum pump is also required.
Accordingly, it is therefore an object of the present invention to provide a cleaning apparatus and a cleaning method, by which an object to be processed is not subjected to a bad influence from the chemical process during the drying process.
It is the other object of the present invention to provide a cleaning apparatus which has a high degree of freedom in design thereby to clean the objects rapidly and miniaturize the apparatus itself, and a cleaning method realized by using the cleaning apparatus.
It is the further object of the present invention to provide a cleaning apparatus which is capable of reducing a capacity of the chamber thereby to decrease a wall thickness of the chamber and an output required for the vacuum pump, and a cleaning method realized by using the cleaning apparatus.
It is the other object of the present invention to provide a cleaning apparatus and a cleaning method, by which it is possible to execute the drying process more effectively.
It is the other object of the present invention to provide a cleaning apparatus which is capable of preventing an occurrence of water marks on surfaces of the object.
It is the other object of the present invention to provide a cleaning apparatus in which a processing bath and a drying section are separated from each other thereby to prevent mist etc. of treatment liquids from entering into a drying chamber thereby to accomplish a stable drying performance of the apparatus, and a cleaning method realized by using the cleaning apparatus.
As a first feature of the present invention, the above-mentioned mentioned objects described above can be accomplished by a cleaning apparatus for cleaning an object to be processed, the apparatus comprising:
a processing bath for storing processing liquid in which the object is immersed;
a drying chamber arranged above the processing bath and provided with an opening which is disposed between a body of the drying chamber and the processing bath and through which the object is transported, the opening being capable of closing;
transporting means for transporting the object between the processing bath and the drying chamber through the opening;
introducing means for introducing inert gas into the drying chamber in order to prevent an atmosphere in the processing bath from moving to the drying chamber; and
filling means for filling the drying chamber with an atmosphere of organic solvent.
As a second feature of the present invention, the above-mentioned objects described above can be also accomplished by a cleaning apparatus for cleaning an object to be processed, the apparatus comprising:
a processing bath for storing processing liquid in which the object is immersed;
a drying chamber arranged above the processing bath and provided with an opening which is disposed between a body of the drying chamber and the processing bath and through which the object is transported, the opening being capable of closing;
transporting means for transporting the object between the processing bath and the drying chamber through the opening;
screening means for screening the opening by a current of inert gas; and
filling means for filling the drying chamber with an atmosphere of organic solvent.
As a third feature or the present invention, the above-mentioned objects described above can be also accomplished by a cleaning apparatus for cleaning an object to be processed, the apparatus comprising:
a processing bath for storing processing liquid in which the object is immersed;
a drying chamber arranged above the processing bath and provided with an opening which is disposed between a body of the drying chamber and the processing bath and through which the object is transported, the opening being capable of closing;
transporting means for transporting the object between the processing bath and the drying chamber through the opening;
filling means for filling the drying chamber with an atmosphere of organic solvent; and
screening means for screening the opening by a current of inert gas;
wherein the screening means includes a pair of first and second doors arranged so as to open and close the opening, the first door having a leading end formed to oppose the second door and provided with an exhaust port for discharging inert gas, the second door having a leading end formed to oppose the first door and provided with an intake port for the inert gas, whereby a current of the inert gas is formed between the leading end of the first door and the leading end of the second door, for screening the opening since the inert gas discharged from the exhaust port of the first door is sucked through the intake port of the second door, in a closing state of the first and second doors.
A fourth feature of the present invention resides in the cleaning apparatus in accordance with any one of the first feature to the third feature, further comprising open and shut means for opening and shutting the opening, alternatively.
A fifth feature of the present invention resides in the cleaning apparatus in accordance with any one of the first feature to the third feature, further comprises open and shut means for alternatively opening and shutting the opening, the first open and shut means in a shutting state thereof also sealing the drying member of the first open and shut means.
A sixth feature of the present invention resides in the cleaning apparatus in accordance with the fifth feature, wherein the filling means includes a nozzle for ejecting gas containing the organic solvent into the drying chamber, the nozzle consisting of at least two inside and outside pipes of different diameters, which engage with each other so that respective circumferential faces thereof are apart from each other; and
wherein the inside pipe is provided, in an axial direction thereof, with a plurality of gas outlets at intervals of a predetermined distance, while the outside pipe is provided, in an axial direction thereof, with a plurality of gas outlets at intervals of a length shorter than the predetermined distance.
As a seventh feature of the present invention, the above objects can be also accomplished by a cleaning method of cleaning an object to be processed, the cleaning method comprising the steps of:
(a) transporting the object before processing from a drying chamber into a processing bath through a lower opening formed in the drying chamber while retaining the object by a retaining member carried on the drying chamber""side;
(b) storing processing liquid in the processing bath before or after transporting the object before processing from drying chamber into the processing bath and subsequently immersing the object in the processing liquid;
(c) transporting the object after processing from the processing bath into the drying chamber; and
(d) filling the drying chamber with an atmosphere of organic solvent and drying the object after processing in the drying chamber.
An eighth feature of the present invention resides in the cleaning method in accordance with the seventh feature, further comprising a step of closing the opening after transporting the object after processing to the drying chamber.
A ninth feature of the present invention resides in the cleaning method in accordance with the seventh or eighth feature, further comprising a step of replacing an atmosphere in the drying chamber with inert gas, before bringing the object before processing from outside into the drying chamber.
A tenth feature of the present invention resides in the cleaning method in accordance with the seventh or eighth feature, further comprising a step of replacing an atmosphere in the drying chamber with inert gas while exhausting an atmosphere in the drying chamber, before bringing the object before processing from outside into the drying chamber.
An eleventh feature of the present invention resides in the cleaning method in accordance with the seventh or eighth feature, further comprising a step of replacing an atmosphere in the drying chamber with inert gas while exhausting an atmosphere in the drying chamber, before filling the drying chamber with the atmosphere of organic solvent.
A twelfth feature of the present invention resides in the cleaning method in accordance with the seventh or eighth feature, after executing the step (d), further comprising a step of introducing inert gas into the drying chamber for recovering the drying chamber of an atmospheric pressure while decompressing the drying chamber, wherein the supply of inert gas during the recover of the drying chamber of an atmospheric pressure is controlled so that a supply volume of the inert gas per unit time increases as time passes.
A thirteenth feature of the present invention resides in the cleaning method in accordance with the seventh or eighth feature, wherein the step (b) comprises the steps of:
executing chemical cleaning of the object;
executing water cleaning of the object; and
executing ozone cleaning of the object after the water cleaning.
A fourteenth feature of the present invention resides in the cleaning method in accordance with the thirteenth feature, wherein the step (b) further comprises a step of executing additional water cleaning of the object after the ozone cleaning.
According to the first feature of the invention, owing to the current of inert gas directing from the drying chamber toward the opening, it is possible to prevent the entering of chemicals from the processing bath to the drying chamber. Further, since the forthcoming process in the next processing bath can be prepared while the drying process is executed, it is possible to improve throughput of the cleaning apparatus. Additionally, since the arrangement allows the drying chamber and the processing bath to be designed under respective conditions independent of each other, it is possible to optimize the cleaning process and further miniaturize the cleaning apparatus because of the enhanced degree of freedom in the process design. Moreover, since the above-mentioned arrangement allows the volume of the drying chamber to be reduced, it is possible to reduce the wall thickness of the drying chamber and the processing bath when it is required to decompress the drying chamber while filling up with the atmosphere of the organic solvent. In addition, it is possible to make the decompression with the low-powered vacuum pump.
According to the second feature to the fourth feature of the invention, owing to the provision of the screening means for screening the opening by the current layer of inert gas, it is possible to screen the processing bath from the drying chamber at the chemical processing for the object, so that the entering of chemicals from the processing bath to the drying chamber can be prevented.
According to the third feature of the invention, when closing the opening by the first and second doors, the clearance between the first and second doors can be screened by the flow of inert gas. Accordingly, it is possible to prevent an invasion of the chemical atmosphere from the processing bath to the drying chamber, furthermore.
According to the fourth feature of the invention, by the open and shut means for opening and shutting the opening of the drying chamber, it is possible to screen the drying chamber from the processing bath at the time of drying the object, so that the object during the drying process is hardly subjected to bad influences derived from the chemicals in the processing bath.
According to the fifth feature of the invention, by separating the drying member from the processing bath in a leak-tight manner at the time of drying the object, the object during the drying process is not subjected to the bad influences derived from the chemicals in the processing bath.
Meanwhile, if gas is introduced into a pipe through an end thereof and then ejected into the drying chamber through gas outlets provided along an axial direction of the pipe, there would be caused a tendency that the closer the gas outlet approaches the other end of the pipe, the less a volume of gas ejected from the gas outlet becomes. Further, in case of ejecting heated gas, there is a tendency that the closer the gas outlet approaches the other end of the pipe, the lower a temperature of gas ejected from the gas outlet gets. According to the sixth feature of the invention, since respective gas flows ejected through a small number of gas outlets on the inside pipe are once joined in a space defined between the inside pipe and the outside pipe and then supplied into the drying chamber through the gas outlets on the outside pipe, it is possible to reduce the differences in volume and temperature of the ejected gas among the gas outlets furthermore.
According to the cleaning method as the seventh feature of the invention, since the drying chamber is separated from the processing bath, the forthcoming process in the next processing bath can be prepared while the drying process is executed, so that the throughput of the cleaning apparatus can be improved. Additionally, since the arrangement allows the drying chamber and the processing bath to be designed under respective conditions independent of each other, it is possible to optimize the cleaning process and further miniaturize the cleaning apparatus because of the enhanced degree of freedom in the process design. Moreover, since the above-mentioned arrangement allows the volume of the drying chamber to be reduced, it is possible to reduce the wall thickness of the drying chamber and the processing bath when it is required to decompress the drying chamber while filling up with the atmosphere of the organic solvent. In addition, it is possible to make the decompression with the low-powered vacuum pump.
According to the eighth feature of the invention, it is possible to screen the drying chamber from the processing bath at the time of drying the object, so that the object during the drying process is hardly subjected to bad influences derived from the chemicals in the processing bath.
According to the ninth feature of the invention, if only the atmosphere of the drying chamber is replaced with predetermined inert gas prior to the loading of the object into the drying chamber, it is possible to lighten contact between oxygen and the object during its movement from the preceding process chamber up to the present cleaning apparatus and to restrict the natural growth of an oxide film. Moreover, as the replacement of inert gas to be executed again during the cleaning of the object can be started from a state having a lower oxygen concentration than that of the air outside, it is possible to shorten time required for lowering the concentration of oxygen to its permissible value remarkably.
According to the tenth and eleventh features of the invention, by supplying the inert gas in the drying chamber while exhausting it, it is possible to enhance an efficiency in replacing the atmosphere in the drying chamber with the inert gas.
According to the twelfth feature of the invention, it is possible to prevent particles on the inner wall of the drying chamber from flying up by the inert gas flows introduced thereinto and sticking on the object after cleaning or drying.
According to the thirteenth feature of the invention, by applying the ozone cleaning for forming a thin oxide film on the object after its chemical and water cleaning, it is possible to prevent an occurrence of water marks on a surface of the object.
The above and other features and advantages of this invention will become apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference had to the attached drawings showing a preferred embodiment of the invention.